Design And Fabrication Of New Kinds Of Guided-mode Resonance Devices

Guided-mode resonance filters(GMRFs)have drawn a great deal of attention because of their superior spectral response,such as very high peak efficiency,narrow band,low sideband,etc.,and as a result there have been some very promising applications developed in numerous fields including narrow band filters,sensors,optical modulators and so on.Guided-mode resonance only occurs over small parameter ranges,meaning the spectral response of a GMRF will change significantly depending on the incident conditions and structural parameters.This characteristic is quite advantageous for sensor applications,but simultaneously introduces many obstacles to the fabrication and use of GMRF for other applications.In this dissertation,we will start from the view of real life application,study the influence of errors of structure parameters and incident conditions on the spectral performance of GMR device,and then propose a new way to eliminate the influence by errors compensation.A kind of polarization-insensitive GMRF is designed,and the principle of using them to reproduce color images is discussed.Moreover,self-assembly methods of fabricating nanosphere GMR device is present,and a sample with the resonance wavelength at 402.3nm is fabriciated.In this dissertation,the rigorous coupled wave analysis(RCWA)and finitedifference time-domain(FDTD)method are presented,and a general diffraction analysis of subwavelength gratings by them is introduced.The applicable scopes of the two methods are compared,which provide a reference for calculations in different situations later.Based on the RCWA,the influence of errors of structure parameters and incident angles on the spectral response of GMRF is discussed in detail,and method of using structure parameters to compensate errors is presented.Besides,a layer with adjustable refractive index(PDLC)is added to increase the compensation scope.According to the typical manufacturing flow of GMRF,amending the subsequent structural parameters from later in the process can compensate for errors caused by parameters early in the process.For the tunable GMRF designed in this dissertation,we can use the parameters of grating layer to compensate errors that originate from the waveguide layer during the manufacture process,and the comprehensive errors can be elimated by adjust the refractive index of PDLC during use.What's more,the fluctuation of resonant peak caused by the change of incident angles can be compensated by PDLC too in real time,and a maximum angular compensation range of about ±4.2° is obtained without affecting the filtering performance.The proposed error compensation mechanism can be used to reduce the difficulty of fabricating GMRFs and improve the performance of them.Besides,it can elimate some limitations of using GMRF in practice.Starting from the basic principle of waveguide optics,and combining with the analysis of wavevector diagram,a conclusion is derived that two modes will be excited simultaneously in GMRF while azimuth angle is equal to 90°(full conical incidence),and then polarization-insensitive may be obtained.A kind of GMR color filter based on multilayer resonant grating structure under this incident situation is designe,and the influences of the waveguide thickness and fill factor on the characteristic of the device are investigated by using the RCWA method,then optimized structure parameters for three primary colors are obtained.The calculated spectral reflectance curves of the three given grating structures are all showing wonderful coincidence at the resonant wavelengths and similar shapes for different polarized incidence while the fill factor is equal to 0.36.Moreover,field distribution analysis by FDTD Solution points out that two symmetric modes are excited between the waveguide layer and substrate under full conical incidence which just proves the conclusion of previous theoretical study for how polarization-independent could be happening.A method of utilizing polarization-independent GMRF array to reproduce colored images is proposed.Color details of master image can be reappeared by distributing three kinds of color filters.Simulation results show that the master image can be reproduced realistic not only with the polarized incident light,but also with the unpolarized natural light.This method is different from the way using in traditional press which mixing pigment together,but utilizing GRMF acted as ‘optical pigment'.With the development of micro-nano manufacturing technology,it is possible to fabricate gratings with different period or depth on one substrate,so colored image can be reappearred by distributing the three basic grating structures.The assumed ‘optical printer' can totally escape from printing ink,and can be used in anti-fake and printing areas.Self-assembly methods of nanosphere are compared,and the way of dip-coating is selected to fabricate nanospher GMRF according to our experiment condition.The nanospheres will form face-centered cubic(fcc)colloidal crystal films by force analysis.The spectral performance of GMRF with nanosphere grating is analyzed,and the influences of waveguide depth,radius of nanosphere,incident angles,polarization and the precedence order of coating on the reflectivity of this device are investigated respectively.In the end,monodisperse nanospheres with radius euqals to 260 nm are used to fabricate grating layer of GMRF,then the structural formation and spectral property of the device are tested,and the results show that the nanospheres are arranged in regular hexagon and the resonant wavelength is 402.3nm.